Control for selecting automated transmission system shift strategy

ABSTRACT

A control for an automated mechanical transmission system ( 10 ) including, an automated master clutch ( 20/39 ). The system controller ( 46 ) will sense vehicle operating conditions ( 54 ) to command the most appropriate of dynamic shifts performed with the master clutch engaged or dynamic shifts performed by disengaging and then re-engaging the master clutch.

RELATED APPLICATIONS

This application is a continuation of copending U.S. application Ser.No. 10/470,476, assigned to Eaton Corporation, assignee of thisapplication, the contents of which are incorporated by reference hereinin their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to control for an automated mechanicaltransmission system and in particular to a control for selecting, as afunction of sensed system operating parameters, either (i) a shiftsequence involving master clutch disengagement or (ii) a shift sequencenot involving master clutch disengagement, in an automatic mechanicaltransmission system including an automated master friction clutch.

2. Description of the Prior Art

Automate mechanical transmission systems (i.e., systems havingtransmissions wherein gear ratios are engaged and disengaged by jawclutches) having automated master clutch operators are known in theprior art as may be seen by reference to U.S. Pat. Nos. 4,081,065;4,361,060; 4,648,290; 4,936,428; 5,960,916; 5,947,847; and 5,634,867,the disclosures of which are incorporated herein by reference. Automatedmechanical transmission systems not having an automatic master clutchactuator and requiring manual master clutch operation, usually only tolaunch the vehicle, are also known in the prior art as may be seen byreference to U.S. Pat. Nos. 6,145,399; 5,582,558; 6,146,310; 5,272,939;5,335,566; and 5,425,689, the disclosures of which are incorporatedherein by reference.

The prior art automated transmissions systems not having an automatedmaster clutch actuator, by necessity, utilized a shift sequence fordynamic automatic shifting not requiring disengagement of the vehiclemaster clutch. Typically, engine fueling was controlled to relievetorque lock, allowing a shift from a previously engaged ratio intoneutral and then the engine was caused to rotate at a substantiallysynchronous speed for engaging a target ratio, all with the masterclutch remaining engaged. Systems of this type may be seen by referenceto U.S. Pat. Nos. 4,850,263; 5,820,104; 4,593,580; 5,582,558; 6,126,570;and 6,145,399, the disclosures of which are incorporated herein byreference.

The prior art automated mechanical transmission systems having anautomated master clutch actuator tended to utilize a shift strategy orsequence for all dynamic shifts which included disengaging and thenre-engaging the master friction clutch at least once during each shift,regardless if that shift could have been acceptably and/or preferablyperformed without disengaging and re-engaging the master clutch.

SUMMARY

In accordance with the present invention, the drawbacks of the priorart, automated mechanical transmission systems are minimized byproviding a control for an automated mechanical transmission systemhaving an automated master clutch operator which, on a shift-by-shiftbasis, and as a function of sensed vehicle operating conditions, willdetermine if (i) a shift strategy retaining the master clutch engaged or(ii) a shift strategy involving disengaging and re-engaging the masterclutch, is most appropriate for a dynamic shift from an existing gearratio into a target gear ratio.

Accordingly, it is an object of the present invention to provide a newand improved automated mechanical transmission system having automaticmaster clutch operator which will evaluate and implement the mosteffective of (i) a shift sequence retaining the master clutch engagedand (ii) a shift sequence involving disengaging and then re-engaging themaster clutch, for dynamic shifts from an engaged ratio into a targetgear ratio.

This and other objects and advantages of the present invention willbecome apparent from a reading of the following description of thepreferred embodiment taken in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a vehicular drivetrain using anautomated mechanical transmission system including an automatic masterclutch operator.

FIG. 2 is a schematic illustration, in flow chart format, of the controlof the present invention.

FIG. 3 is a schematic illustration of a preferred engine controlsequence for relieving torque lock in a shift sequence retaining themaster clutch engaged.

FIGS. 4A and 4B are schematic illustrations, in flow chart formats of analternate embodiment of the present invention.

DETAILED DESCRIPTION

An automated vehicular drivetrain system 10 using the shift sequenceselection control technique of the present invention is schematicallyillustrated in FIG. 1. In system 10, a change-gear transmission 12comprising an automatically shifted main transmission section 14connected in series with a splitter-type auxiliary transmission section16 is drivingly connected to an internal combustion engine 18, such as awell-known gasoline or diesel engine, by an automatically operatedmaster friction clutch 20. Preferably, auxiliary transmission section 16is of the three-layer, four-speed combined splitter/range type, asillustrated in U.S. Pat. Nos. 4,754,665 and 5,390,561, the disclosuresof which are incorporated herein by reference.

Engine 18 includes a crankshaft 22, which is attached to a drivingmember 24 of master clutch 20, which is normally frictionally engagedwith a driven member 26, which is attached to the input shaft 28 of thetransmission. A transmission output shaft 30 extends from the auxiliarytransmission section 16 for driving connection to the vehicular drivewheels, as through a drive axle 31 or the like. For purposes ofillustration, transmission 12 is illustrated as a(2+1).times.(2).times.(−2) type transmission providing nine or tenselectable forward ratios. Transmissions of this general type are wellknown in the prior art and are sold by the assignee of this application,EATON CORPORATION, under the trademark “Super-10” and may be seen ingreater detail by reference to U.S. Pat. Nos. 6,015,366; 5,974,906; and5,974,354, the disclosures of which are incorporated herein byreference.

An inertia or input shaft brake 29 may be provided to selectively retardthe rotational speed of input shaft 28. The engine may also include anengine brake device such as engine compression brake ECB.

Transmission system 10 further includes rotational speed sensors 32 forsensing engine rotational speed (ES), 34 for sensing input shaftrotational speed (IS), and 36 for sensing output shaft rotational speed(OS), and providing signals indicative thereof. A sensor 37 provides asignal THL indicative of throttle pedal position. The signal is usuallya percentage (0% to 100%) of fuel throttle position. Engine 18 may beelectronically controlled, including an electronic controller 38communicating over an electronic data link (DL) operating under anindustry standard protocol such as SAE J-1922, SAE J-1939, ISO 11898 orthe like. An automated actuator 39 may be utilized to selectively engageand disengage normally engaged master clutch 20, as is well known in theprior art. A sensor 20A maybe provided to sense the condition of clutch20 and to provide a signal C indicative thereof.

Clutch controller 39 may be of any known type, such as a piston operateddevice, a ball ramp operated device or the like, see for example U.S.Pat. Nos. 4,081,065; 4,361,060; 4,865,173; 5,964,330; and 6,022,295.

A shift actuator 40 is provided to control shifting of the transmissionsections. Shift actuator 40 is preferably an X-Y shift actuator, whichby way of example may be of the types illustrated in U.S. Pat. Nos.5,481,170; 5,281,902; 4,899,609; and 4,821,590. Actuator 40 willpreferably include a position sensor 40A operable to sense the X-Yposition of a shift member and to provide signals indicative thereof.X-Y position sensors are known in the prior art and examples thereof maybe seen by reference to U.S. Pat. Nos. 5,743,143; 5,894,758; 5,950,491;and 5,911,787, the disclosures of which are incorporated herein byreference

A shift selector 42 provides a signal GRs of the mode of operatorselected by the operator. System 10 includes a control unit, preferablya microprocessor-based control unit 46 of the type illustrated in U.S.Pat. Nos. 4,595,986; 4,361,065; and 5,335,566, the disclosures of whichare incorporated herein by reference, for receiving input signals 54 andprocessing same according to predetermined logic rules to issue commandoutput signals 56 to system actuators, such as engine controller 38,clutch actuator 39, auxiliary section shift actuator 40, and the like.Control unit 46 may include a timing circuit or clock 48.

FIG. 1A illustrates a typical jaw clutch assembly 70 for selectivelyengaging and disengaging a gear 72 to a shaft 74, such as a transmissionmain shaft, for engaging and disengaging a transmission ratio. Briefly,jaw clutch member 76 is splined to shaft 74 for axial movement relativethereto and rotation therewith. Jaw clutch member 76 carries externalclutch teeth 78 for engaging internal clutch teeth 80 formed in theinner diameter bore of gear 72. The jaw clutch member 76 is axiallypositioned by a shift fork (not shown) or the like. The shift fork istypically axially positioned by a shift rail, a shift shaft, a ball rampor ball screw, a piston, or a functionally similar device.

As is known, to disengage a jaw clutch in a vehicular mechanicaltransmission, especially in a heavy-duty vehicle, it is necessary torelieve torque lock at the engaged jaw clutch. If opening the masterclutch 20 is not desirable, torque lock can be relieved by fueling theengine to cause assumed zero driveline torque and/or by forcing torquereversals which will positively cause crossings of zero drivelinetorque.

Fully or partially automated mechanical transmission systems that, upondetermining that a dynamic shift from a currently engaged ratio intoneutral and then into a target ratio is desirable, will, whilemaintaining the vehicle master friction clutch engaged, initiateautomatic fuel control to cause reduced torque across the jaw clutchesto be disengaged, are known in the prior art as may be seen by referenceto U.S. Pat. Nos. 4,850,236; 5,820,104; 5,582,558; 5,735,771; 5,775,639;6,015,366; and 6,126,570, the disclosures of which are incorporatedherein by reference. These systems include systems that attempt to fuelthe engine to achieve a sustained zero driveline torque, and systemsthat force torque reversals, see U.S. Pat. No. 4,850,236. These systems,upon sensing a neutral condition, will, while maintaining the masterclutch engaged, cause the engine to rotate at a speed determined tocause synchronous conditions for engaging the target ratio.

Control of engine torque to achieve a desired output or flywheel isknown as and may be seen by reference to U.S. Pat. No. 5,620,392, thedisclosure of which is incorporated herein by reference.

Engine torque as used herein refers to a value indicative of an enginetorque, usually gross engine torque, from which an output or flywheeltorque may be calculated or estimated. The relationship of gross enginetorque to flywheel torque is discussed in U.S. Pat. Nos. 5,509,867 and5,490,063, the disclosures of which are incorporated herein byreference.

One or more engine torque value may be commanded on, or read from, andindustry standard data line, DL, such as SAE J-1922, SAE J-1939 orIS011898 compliant datalink.

According to one embodiment of the present invention, upon sensing thata shift from an engaged ratio to neutral, without disengaging the masterclutch 20, is required, the engine is first commanded to ramp to a valueof engine torque determined or calculated, based upon sensed systemoperating parameters, to correspond to zero driveline torque.

Referring to FIG. 3, if the shift initiates at a drive condition 110,the engine torque will be commanded to ramp down 112 to the calculatedvalue 114 assumed to correspond to the zero driveline torque condition.Similarly, if the shift to neutral initiates at a coast condition 116,the engine torque will be commanded to ramp up 118 to the calculatedvalue 114. Preferably, the slope of the ramps 112 and 116 (i.e., therate of change of engine torque) will be functions of the ratio beingdisengaged and/or current throttle position THL. Upon achieving theassumed zero driveline torque condition 120 (at time T,) the engine willbe commanded to remain at this condition 122 for a period of T time(T.sub.2−T.sub.1). The period of time (T.sub.2−.sub.1) is typicallyabout 150-300 milliseconds. At expiration of that period of time 124,the sensed velocity of a shift member, such as for example, a shift forkor shift finger, is compared to a reference value REF. If the shiftmember velocity equals or exceeds the reference value((d/dt(SL.sub.Y−Y))>REF), this indicates that the shift member is movingat a rate towards jaw clutch disengagement indicative of non-torque lockconditions and a torque bump routine is not necessary or desirable. Insuch conditions, the engine will be commanded to continue generating anoutput torque assumed to correspond to zero driveline torque (solid line126) until transmission neutral is sensed.

If the sensed shift member velocity does not equal or exceed thereference value ((d/dt(SL.sub.Y−Y)<REF), than torque lock conditions mayexist and a torque bump fueling routine of the engine (dashed lines 128)to forced torque reversals (130) at the jaw clutch will commence untilneutral is sensed and/or a time period expires. The magnitude and/orshape of the torque bumps 128 may vary with time.

As may be seen, system 10 has the ability to perform dynamic shiftseither by a sequence not involving disengaging and the re-engaging themaster clutch or by a sequence wherein the master clutch is disengagedand then re-engaged.

Prior art automated systems with automatic clutch actuators tended to doall dynamic shifting utilizing the master clutch or all dynamic shiftingwithout utilizing the master clutch. Dynamic shifting without use of themaster clutch is generally desirable as no wear to the clutch componentsoccurs and shift quality is generally better than shifting with masterclutch disengaging and re-engaging. However, under certain vehicleoperating conditions, such as when shifting in low gears on gradients,using the master clutch can reduce shift times and assure thatsynchronous conditions can be reached in a reasonable time.

According to the present invention, the system 10 decides,shift-by-shift which dynamic shift strategy is appropriate to currentvehicle operating conditions. In a preferred embodiment, shifting withthe master clutch remaining engaged is the preferred shift strategy, andwill be implemented unless the system senses the existence of conditionsindicating the need for a master clutch disengagement/re-engagement typeshift. If such conditions are sensed, a master clutchdisengagement/re-engagement shift sequence will be commanded, seeflowchart of FIG. 2.

There are various operating conditions which call for dynamic shiftingusing master clutch disengagement. When in a “low ratio”, which is ahigh ratio of input shaft speed to output shaft speed, and traveling upa grade, it may be difficult to cause a zero driveline torque if thegrade is steep and it may also be difficult to decelerate the enginequickly enough to cause substantially synchronous conditions forengaging the jaw clutch associated with a relatively low gear ratio.This may even be true if an engine brake, ECB, is utilized. In suchsituations, disengaging the clutch will assure a torque break forshifting to neutral and by engaging the jaw clutch first and then themaster clutch, the slip of the master clutch will allow a considerablywider synchronous window for engaging the target ratio (GR.sub.T) thanwill the backlash of a jaw clutch.

Further, with the master clutch disengaged, an inertia brake 29 willhave a much greater decelerating effect on the input shaft for quickerupshifting. Further, if the torque reversal technique, line 128 in FIG.3, does not result in a rapid shift to neutral, the control may thencause nominal engine output torque and a brief master clutchdisengagement.

It is noted that, in certain operating conditions, engine brakes, suchas engine compression brakes, may be somewhat ineffective to causesufficiently rapid engine deceleration and/or may be somewhat slow torespond. Accordingly, if an extremely rapid torque interruption and/orinput shaft deceleration is required, a shift strategy using masterclutch disengagement is preferred.

The clutch actuator 39 will be used to engage clutch 20 in a modulatedmanner to launch the vehicle from stop, as well as providing the abilityto do dynamic shifting in a shift sequence involving disengagement andre-engagement of the master clutch. Examples of clutch controls forvehicle launch may be seen by reference to U.S. Pat. Nos. 4,081,065;5,314,050; 5,404,301; 5,630,713; and 5,643,867. Dynamic shifting refersto shifting while the vehicle is moving, usually in the forwarddirection, and the clutch has been fully engaged. A typical up-shiftsequence utilizing the master clutch will involve (i) disengaging themaster clutch to break torque, (ii) shifting from engagement of gearratio GR into neutral, (iii) decelerating the input shaft toward asubstantially synchronous speed, (iv) engaging the jaw clutch associatedwith the target gear ratio GR.sub.T, and (v) re-engaging the masterclutch as engine speed falls within a relatively wide window ofsynchronous engine speed

Logic for evaluating the feasibility of a particular shift and/or foridentifying the most desirable target gear ratio (GR.sub.T) in automatedmechanical transmission systems is known in the prior art, see U.S. Pat.Nos. 5,272,939; 5,335,566; 5,533,946; 6,066,071; 6,146,310; and6,149,545, the disclosures of which are incorporated herein byreference. According to one prior art system, skip shifts without masterclutch disengagement or engine braking, then single shift without masterclutch disengagement but with engine braking are evaluated in sequencefor feasibility, and, if feasible, initiated (see U.S. Pat. No.6,149,545). In a preferred embodiment of the present invention, if asingle shift without master clutch disengagement but with engine brakingis not feasible, then a single shift with master clutch disengagement isevaluated for feasibility, and, if feasible, initiated (see FIGS. 4A and4B).

Accordingly, it may be seen that a new and improved transmission systemand shift selection strategy therefore, is provided.

Although the present invention has been described with a certain degreeof particularity, it is understood that the description of the preferredembodiment is by way of example only and that numerous changes to formand detail are possible without departing from the spirit and scope ofthe invention as hereinafter claimed.

1-29. (canceled)
 30. A method for controlling automatic upshifting in avehicular automated mechanical transmission system comprising afuel-controlled engine, an input shaft deceleration device,multiple-speed mechanical transmission, a master clutch and a controllerfor receiving input signals including one or more of signals indicativeof engine speed, engine torque, transmission engaged gear ratio,operator throttle setting and vehicle speed, and to process said inputsignals in accordance with logic rules to issue command output signalsto transmission system actuators including a transmission actuatoreffective to shift said transmission, an input shaft deceleration deviceactuator effective to operate said input shaft deceleration device, anda clutch actuator effective to engage and disengage said master clutch,the method comprising the steps of: establishing an upshift feasibilitycriteria for determining feasibility of upshifts into a target gearratio (GR_(T)); and performing at least one of the following steps uponsensing a requirement for an upshift from an engaged gear ratio (GR):(a) determining if a single upshift without use of said input shaftdecelerating device and without disengaging the master friction clutchis feasible and, if feasible, commanding a single upshift from thecurrently engaged ratio without using said input shaft deceleratingdevice and without disengaging the master friction clutch; (b)determining if a single upshift using said input shaft deceleratingdevice and without disengaging the master friction clutch is feasibleand, if feasible, commanding a single upshift from the currently engagedratio using said input shaft decelerating device and without disengagingthe master friction clutch; (c) determining if a single upshift withdisengaging the master friction clutch is feasible and, if so,commanding a single upshift from the currently engaged ratio withdisengaging the master friction clutch; and (d) retaining thetransmission engaged in the currently engaged ratio.
 31. The method ofclaim 30, wherein said input shaft decelerating device is an enginebrake.
 32. The method of claim 30, wherein the criteria includes therequirement that substantial synchronization can be obtained above apredetermined engine speed.
 33. The method of claim 30, wherein thecriteria includes the requirement that at engagement of the targetratio, the vehicle will be capable of at least a predetermined minimumvehicle acceleration.
 34. The method of claim 30, wherein the criteriaincludes the requirement that upshifts into a target gear ratio becompleted within a predetermined maximum period of time.
 35. The methodof claim 30, further comprising the step of commanding the engine toramp to a value of driveline torque that corresponds to about zerodriveline torque.
 36. The method of claim 30, wherein said step ofperforming includes determining whether a single upshift withoutdisengaging the master clutch and with engine braking is feasible. 37.The method of claim 30, wherein all steps of determining are performed.38. A method for controlling automatic upshifting in a vehicularautomated mechanical transmission system comprising a fuel-controlledengine, a multiple-speed mechanical transmission, a master frictionclutch and a controller for receiving input signals including one ormore of signals indicative of engine speed (ES), engine torque,transmission engaged gear ratio (GR), operator throttle setting (THL)and vehicle speed (OS), and to process said input signals in accordancewith logic rules to issue command output signals to transmission systemactuators including a transmission actuator effective to shift thetransmission and a clutch actuator effective to engage and disengage themaster friction clutch, the method comprising the steps of: establishingan upshift feasibility criteria whereby upshifts into a target gearratio (GR_(T)) are considered feasible only if, under sensed vehicleoperating conditions, predetermined conditions are satisfied; andperforming at least one of the following steps upon sensing arequirement for an upshift from an engaged gear ratio (GR): (a)determining if a single upshift without disengaging the master frictionclutch is feasible and, if feasible, commanding a single upshift fromthe currently engaged ratio without disengaging the master frictionclutch; (b) determining if a single upshift with disengaging the masterfriction clutch is feasible and, if so, commanding a single upshift fromthe currently engaged ratio with disengaging the master friction clutch,if not, (c) retaining the transmission engaged in the currently engagedratio.
 39. The method of claim 38, wherein the criteria includes therequirement that substantial synchronization can be obtained above apredetermined engine speed.
 40. The method of claim 38, wherein thecriteria includes the requirement that at engagement of the target gearratio, the vehicle will be capable of at least a predetermined minimumvehicle acceleration.
 41. The method of claim 38, wherein the criteriaincludes the requirement that upshifts into a target gear ratio becompleted within a predetermined maximum period of time.
 42. The methodof claim 38, wherein at least one of said steps of determining includesdetermining whether a single upshift without disengaging the masterclutch and with engine braking is feasible.
 43. The method of claim 38,wherein all steps of determining are performed.
 44. The method of claim38, wherein said step of commanding a single upshift from the currentlyengaged ratio without disengaging the master friction clutch includesthe step of braking the engine.
 45. A vehicular automated mechanicaltransmission system comprising: an automatic master clutch operator; anda system controller utilizing control logic, wherein said controllerselectively evaluates a sl gear ratio.
 46. The system of claim 45,wherein said controller selects at least one of the shift sequences. 47.The system of claim 46, wherein said controller selectively implementsthe selected shift sequence.
 48. The system of claim 45, wherein saidcontroller selectively receives input signals, wherein said inputsignals include signals indicative of at least one of engine speed (ES),engine torque, transmission engaged gear ratio (GR), operator throttlesetting (THL) and vehicle speed (OS).
 49. The system of claim 45,wherein said controller selectively issues output signals, wherein saidoutput signals include signals indicative of at least one of engine fuelcontrol, clutch actuator control, jaw clutch control, and engine brakecontrol.